Limbic encephalitis is a serious neurological disease that causes inflammation in brain limbic system, including hippocampus, thalamus, hypothalamus, and amygdale. Patients with limbic encephalitis often present with memory loss, seizures and/or confusion.
Encephalitis, including limbic encephalitis, fall into two main categories: infectious encephalitis—caused by direct invasion of the brain by an infectious agent, usually a virus and autoimmune encephalitis—caused by the persons own immune system reacting against itself.
Autoimmune limbic encephalitis can be either paraneoplastic limbic encephalitis (PLE) or non-paraneoplastic limbic encephalitis (NPLE). Until the mid-1990s, most cases of non-viral limbic encephalitis were considered to be paraneoplastic.
Paraneoplastic limbic encephalitis (PLE) occurs in a small proportion of people with particular cancers. Most individuals with PLE will turn out to have a cancer in lung, thymus gland, breast or testis. In many cases, PLE can be diagnosed by testing for one of a group of paraneoplastic autoantibodies in blood. The condition may improve or at least stabilise if the cancer is detected and treated effectively.
NPLE has been attributed in many cases to specific antibodies in blood that target the potassium channel, called voltage-gated potassium channel (VGKC) antibody-associated encephalitis. This type of NPLE is believed to cause a reduction in the number of potassium channels, decreasing the control over neuronal synaptic transmission.
An accurate diagnosis of autoimmune encephalitis is particularly important because the disease is potentially treatable, using immunosuppressive drugs such as steroids. A cell based assay in which HEK293 cells transfected with autoantigen serve as a substrate for an unambiguous immunocytochemical assay for antibody detection in patients' serum or CSF is needed. Over the years, multiple attempts to develop an assay where cells transfected with Kv subunits of the VGKC have failed. Currently, VGKC antibody-associated encephalitis is diagnosed using immunoprecipitation techniques based on 125I-α-dendrotoxin-labeled VGKC (dendrotoxin binds to Kv1.1, Kv1.2 and Kv1.6). This test however, is neither accurate nor specific. Accordingly, there exists a need for improved methods of diagnosing and treating autoimmune encephalitis or epileptic seizures.